Research Of Ac Loss Simulating Calculation Of High Temperature Superconductors Based On H Equation

Compared with a single superconducting wire,high-temperature superconducting complex structural models such as stacks,spirals,and cables have advantages in structure,high flexibility in structure,and large current carrying density.Therefore,the superconducting wires with different structures have great development prospects in the medical,military,and other fields.However,the shape of the superconducting portion of the high-temperature superconducting material is elliptical or rectangular,resulting in that the vertical magnetic field generated at the time of energization cannot always be effectively reduced.In this dissertation,the simulation software is used for numerical simulation and simulation calculation.By comparing with the relevant experimental results,the characteristics of AC loss and other characteristics of various superconducting wires and their complex structures are studied and analyzed.Various simulation software and computing technologies have gradually matured with continuous development.So far simple simulation techniques for superconducting material structures have been relatively thorough,while finite element analysis,field-circuit coupled small-system analysis and electricity The system analysis rule is the most commonly used three kinds of numerical simulation methods for current simulation calculations.This dissertation will be based on multiphysics modeling advanced numerical simulation software COMSOL Multiphysics,first based on a single superconducting wire,the traditional two-dimensional finite element simulation model is optimized,based on the H equation to build second generation high temperature superconducting wire material stack structure The finite element simulation model,and after expanding the two-dimensional H equation into a three-dimensional H equation,after performing a series of geometric model optimization and grid optimization,a three-dimensional finite element simulation model of a square line is established,and the three-dimensional model is compared with the two The simulation results of the dimensional model are compared.Then,on this basis,the finite element model of the spiral structure of Bi-2223 high temperature superconducting current limiter was built,the finite element simulation model of YBCO superconducting cable was built,and 14 squares were built for the new wire square line.The square wire cable with an internal radius of 3 mm is used for simulation calculations and related experimental studies have been conducted.The analysis explores how to reduce the AC losses in the helical structure of superconducting wires and the superiority of square-shaped cables compared to YBCO high-temperature superconducting cables.The experimental results show that the three-dimensional and two-dimensional model simulation results and the theoretical calculation results are compared,and the results of the three-dimensional finite element simulation model established in this experiment are confirmed to be reliable.The model construction method and the three-dimensional formula extension can be applied to the later complex three-dimensional model;The superconducting wire of the linear structure can effectively reduce the AC loss by changing the spacing of the single wire spiral coil.For the double wire spiral coil,the AC loss does not decrease significantly when the same current is passed,but the anti-winding does not When the current is flowing,the magnetic field is canceled by the current in the opposite direction in the wire,effectively reducing the AC loss;the square wire superconducting cable has a higher critical current than the YBCO superconducting cable,and the AC loss is lower.